Question

A student wants to project the image of a candle flame on a screen $90cm$ in front of a mirror by keeping the flame at a distance of $15cm$ from its pole a) suggest the type of mirror he should use b) determine the linear magnification in this case c) find the distance between the object and its image

Answer 1

(a)

1. The image is to be taken on the screen.
2. So, the mirror to be used is a concave mirror.

(b) Calculation of linear magnification

Step 1: Given

Object distance, u = $-15cm$

Image distance, v = $-90cm$

Step 2: Formula used and calculation

magnification = -(image distance) / object distance

$$\begin{gathered} m=-\frac{v}{u} \\ =-\frac{-90}{-15} \\ =-6 \end{gathered}$$

(c) Distance between object and image

Distance between the object and image = distance of the screen from the pole of the mirror – distance of the object from pole to mirror

$$\begin{gathered} =(90-15)cm \\ =75cm \end{gathered}$$